Commit-ID: 7b3d2f6e08ed5eb6bcf6912938f7a542405f8e8e Gitweb: http://git.kernel.org/tip/7b3d2f6e08ed5eb6bcf6912938f7a542405f8e8e Author: Thomas Gleixner <[email protected]> AuthorDate: Sat, 19 Nov 2016 13:47:33 +0000 Committer: Thomas Gleixner <[email protected]> CommitDate: Tue, 29 Nov 2016 19:23:15 +0100
x86/tsc: Use X86_FEATURE_TSC_ADJUST in detect_art() The art detection uses rdmsrl_safe() to detect the availablity of the TSC_ADJUST MSR. That's pointless because we have a feature bit for this. Use it. Signed-off-by: Thomas Gleixner <[email protected]> Reviewed-by: Ingo Molnar <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Yinghai Lu <[email protected]> Cc: Borislav Petkov <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Thomas Gleixner <[email protected]> --- arch/x86/kernel/tsc.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index 0ff1ec6..2b27c5a 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -1057,18 +1057,20 @@ static void detect_art(void) if (boot_cpu_data.cpuid_level < ART_CPUID_LEAF) return; - cpuid(ART_CPUID_LEAF, &art_to_tsc_denominator, - &art_to_tsc_numerator, unused, unused+1); - - /* Don't enable ART in a VM, non-stop TSC required */ + /* Don't enable ART in a VM, non-stop TSC and TSC_ADJUST required */ if (boot_cpu_has(X86_FEATURE_HYPERVISOR) || !boot_cpu_has(X86_FEATURE_NONSTOP_TSC) || - art_to_tsc_denominator < ART_MIN_DENOMINATOR) + !boot_cpu_has(X86_FEATURE_TSC_ADJUST)) return; - if (rdmsrl_safe(MSR_IA32_TSC_ADJUST, &art_to_tsc_offset)) + cpuid(ART_CPUID_LEAF, &art_to_tsc_denominator, + &art_to_tsc_numerator, unused, unused+1); + + if (art_to_tsc_denominator < ART_MIN_DENOMINATOR) return; + rdmsrl(MSR_IA32_TSC_ADJUST, art_to_tsc_offset); + /* Make this sticky over multiple CPU init calls */ setup_force_cpu_cap(X86_FEATURE_ART); }
